Manufacturing method of semiconductor device and semiconductor device

ABSTRACT

The technology which can improve the performance of a MOS transistor in which all the regions of the gate electrode were silicided is offered. 
     A gate insulating film and a gate electrode of an nMOS transistor are laminated and formed in this order on a semiconductor substrate. A source/drain region of the nMOS transistor is formed in the upper surface of the semiconductor substrate. The source/drain region is silicided after siliciding all the regions of the gate electrode. Thus, silicide does not cohere in the source/drain region by the heat treatment at the silicidation of the gate electrode by siliciding the source/drain region after the silicidation of the gate electrode. Therefore, the electric resistance of the source/drain region is reduced and junction leak can be reduced. As a result, the performance of the nMOS transistor improves.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of and claims the benefit of priorityunder 35 U.S.C. §120 from U.S. application Ser. No. 11/381,654, filedMay 4, 2006, and claims the benefit of priority under 35 U.S.C. §119from Japanese Patent Application No. 2005-197055 filed on Jul. 6, 2005,the entire contents of which are incorporated hereby by reference.

1. Field of the Invention

The present invention relates to a semiconductor device provided with aMOS transistor in which all the regions of the gate electrode aresilicided, and its manufacturing method.

2. Description of the Background Art

In the CMOS device represented by system-on-chip, densification andmicrofabrication are advanced every year, and the gate length of the MOStransistor is set to 0.1 μm or less, and has reached to tens of nm. Onthe other hand, thickness reduction of the gate insulating film of a MOStransistor is also advanced, and this thickness reduction technology isbecoming indispensable for improvement in short channel characteristicsand the rise of driving current of a MOS transistor as a generationprogresses.

When making microfabrication of the transistor, the increase of gateleakage current accompanying the thickness reduction of a gateinsulating film and the expansion of the depletion layer formed in thesilicon substrate side in the gate electrode which includes polysiliconpose a problem. The increase in gate leakage current leads to theincrease in the power consumption of the whole chip. With the mobileproducts represented by the cellular phone, while employment of ahigh-density CMOS device is required in order to correspond to advancedfeatures, it is necessary to suppress gate leakage current low so thatbattery duration may not become short too much, either. Therefore, theattempt which uses materials with a high relative dielectric constant(it is hereafter called “high-k material”), such as aluminium oxide(Al₂O₃) and tantalum oxide (Ta₂O₅), is performed as a material of a gateinsulating film. Expansion of the depletion layer formed in the gateelectrode which includes polysilicon causes the thickness enhancement ofthe gate insulating film on appearance, and lowering of driving ability.Therefore, in order to make reduction of the width of the depletionlayer concerned and to realize this, the amount of the impurityintroduced into the gate electrode is made to increase, or using ametallic material in which a depletion layer does not generate as a gateelectrode material is performed.

Generally, in order to make threshold voltage of a MOS transistor into amoderate value, it is necessary to choose a gate electrode material inwhich the work function to the silicon substrate has a moderate value.When a metal or a metallic compound is used as a gate electrode materialin order to suppress the generation of a depletion layer, in order toset threshold voltage as a moderate value in each of an nMOS transistorand a pMOS transistor, it is usually necessary to change the gateelectrode material used with those transistors. This makes the CMOSprocess complicated.

Then, the technology of preventing the generation of the depletion layerby siliciding the whole gate electrode while setting up appropriatelythe work function of the gate electrode in both transistors by usingpolysilicon as a gate electrode material and changing the conductivitytype of the impurity which is introduced into the polysilicon concernedwith the nMOS transistor and the pMOS transistor is proposed. The gateelectrode with which all the regions were silicided is called a FUSI(FUlly SIlicided) gate electrode.

The technology regarding a FUSI gate electrode is disclosed in NonpatentLiterature 1. In Patent References 1-5, the technology regarding the MOStransistor which has a gate electrode including silicide is disclosed.

[Nonpatent Literature 1] B. Tavel et al., “Totally Silicided (CoSi₂)Polysilicon: a novel approach to very low-resistive gate (˜2Ω/□) withoutmetal CMP nor etching”, International Electron Device Meeting 2001(IEDM2001).

[Patent Reference 1] Japanese Unexamined Patent Publication No.2003-319670

[Patent Reference 2] Japanese Unexamined Patent Publication No. Hei8-46057

[Patent Reference 3] Japanese Unexamined Patent Publication No. Hei7-245396

[Patent Reference 4] Japanese Unexamined Patent Publication No. Hei11-121745

[Patent Reference 5] Japanese Unexamined Patent Publication No. Hei1-183851

SUMMARY OF THE INVENTION

When manufacturing a MOS transistor provided with the above FUSI gateelectrodes, after performing the silicidation of the source/drain regionof the MOS transistor, all the regions of the gate electrode weresilicided conventionally. Therefore, by the heat treatment performed inthe case of the silicidation of the gate electrode, the silicide in thesource/drain region may cohere and the electric resistance of thesource/drain region concerned may rise.

Furthermore, by the generation of cohesion, the silicide in thesource/drain region may break through the pn junction surface formed inthe boundary of the silicon substrate and the source/drain region, itmay become a configuration over both the silicon substrate and thesource/drain region, and junction leak may increase.

On the other hand, in performing the silicidation of a source/drainregion and a gate electrode simultaneously unlike a described method,usually, since the thickness of the gate electrode is very larger thanthe junction depth of the source/drain region, when all the regions ofthe gate electrode are silicided, the silicide layer in the source/drainregion becomes deep too much, junction leak will go up or short channelcharacteristics will deteriorate.

By the heat treatment performed in the case of the silicidation of thegate electrode, the impurity in the source/drain region may be diffusedtoward the side of the channel region of the MOS transistor, and theshort channel characteristics of the MOS transistor concerned may fall.

Then, the present invention is accomplished in view of theabove-mentioned problem, and it aims at offering the technology whichcan be improved in the performance of a MOS transistor in which all theregions of the gate electrode were silicided.

The first manufacturing method of a semiconductor device of thisinvention comprises the steps of: (a) forming a gate insulating film anda gate electrode of a first MOS transistor over a semiconductorsubstrate, laminating in this order; (b) siliciding all regions of thegate electrode; (c) forming a source/drain region of the first MOStransistor in an upper surface of the semiconductor substrate; and (d)siliciding the source/drain region after the steps (b) and (c).

The second manufacturing method of a semiconductor device of thisinvention comprises the steps of: (a) forming a gate insulating film anda gate electrode of a first MOS transistor over a semiconductorsubstrate, laminating in this order; (b) siliciding the gate electrodepartially; (c) forming a source/drain region of the first MOS transistorin an upper surface of the semiconductor substrate; and (d) silicidingsimultaneously the source/drain region and all regions of a portionwhich is not silicided in the gate electrode after the steps (b) and(c).

The third manufacturing method of a semiconductor device of thisinvention comprises the steps of: (a) forming a gate insulating film anda gate electrode of a first MOS transistor over a semiconductorsubstrate, laminating in this order; (b) forming a semiconductor layerover the semiconductor substrate at a side of the gate insulating filmand the gate electrode so that an upper surface may be located up ratherthan an upper surface of a portion over which the gate insulating filmis formed in the semiconductor substrate; (c) forming a source/drainregion of the first MOS transistor in the semiconductor layer; (d)siliciding the source/drain region; and (e) siliciding all regions ofthe gate electrode after the step (d).

The first semiconductor device of this invention comprises: asemiconductor substrate; and a MOS transistor formed over thesemiconductor substrate; wherein the MOS transistor includes: asource/drain region in which a silicide layer is formed; and a gateelectrode with which all regions are formed with silicide which excelsthe silicide layer of the source/drain region in thermostability.

The second semiconductor device of this invention comprises: asemiconductor substrate; and a MOS transistor formed over thesemiconductor substrate; wherein the MOS transistor includes: asource/drain region in which a silicide layer is formed; and a gateelectrode with which all regions are formed with silicide; wherein whatgenerates a silicide reaction at low temperature rather than a metallicmaterial of the silicide of the gate electrode is used for a metallicmaterial of the silicide layer of the source/drain region.

The third semiconductor device of this invention comprises: asemiconductor substrate; and a first and a second MOS transistors formedover the semiconductor substrate; wherein the first MOS transistor has asource/drain region in which a silicide layer is formed, and a gateelectrode with which all regions are formed with silicide including ntype impurities; the second MOS transistor has a source/drain region inwhich a silicide layer is formed, and a gate electrode with which allregions are formed with silicide including p type impurities; and thegate electrode of the second MOS transistor is formed more thinly thanthe gate electrode of the first MOS transistor.

The fourth semiconductor device of this invention comprises: asemiconductor substrate; and a first MOS transistor formed over thesemiconductor substrate; wherein the first MOS transistor includes: agate electrode which is formed via a gate insulating film over thesemiconductor substrate, and with which all regions include silicide;and a source/drain region which includes a silicide layer formed overthe semiconductor substrate in a top end; wherein an upper surface ofthe silicide layer is located in 5 nm or more upper part rather than anupper surface of a portion over which the gate insulating film is formedin the semiconductor substrate.

According to the first manufacturing method of a semiconductor device ofthis invention, since a silicidation of a source/drain region isperformed after a silicidation of a gate electrode, in the case of thesilicidation of the gate electrode, silicide does not exist in thesource/drain region. Therefore, silicide does not cohere in thesource/drain region by the heat treatment by the silicidation of thegate electrode. Therefore, the adverse effect by cohesion of silicidecan be eliminated, and junction leak can be reduced while being able toreduce the electric resistance of the source/drain region. As a result,the performance of the first MOS transistor can be improved.

According to the second manufacturing method of a semiconductor deviceof this invention, since a silicidation of a source/drain region isperformed after a partial silicidation of a gate electrode, in the caseof the partial silicidation of the gate electrode, silicide does notexist in the source/drain region. Therefore, silicide does not cohere inthe source/drain region by the heat treatment by the partialsilicidation of the gate electrode. Since the silicidation of theremaining portion of the gate electrode and the silicidation of thesource/drain region are performed simultaneously, in the silicidation ofthe remaining portion of the gate electrode, silicide does not cohere inthe source/drain region. Therefore, the adverse effect by cohesion ofsilicide can be eliminated, and junction leak can be reduced while beingable to reduce the electric resistance of the source/drain region. As aresult, the performance of the first MOS transistor can be improved.

According to the third manufacturing method of a semiconductor device ofthis invention, since a semiconductor layer is formed on a semiconductorsubstrate and a source/drain region is formed in the semiconductorlayer, it becomes difficult for the impurities in the source/drainregion to diffuse to the channel region of the first MOS transistor bythe heat treatment by the silicidation of the gate electrode. Therefore,degradation of the short channel characteristics in the first MOStransistor can be prevented, and the performance can be improved.

Since the source/drain region formed in the semiconductor layer issilicided, the silicide layer in the source/drain region can be thicklyformed by adjusting the thickness of the semiconductor layer. Since itwill be hard to be influenced by heat treatment when the silicide layeris thick, it becomes difficult to generate cohesion of silicide.Therefore, the cohesion generated in the silicide layer of thesource/drain region by the heat treatment by the silicidation of thegate electrode can be suppressed. Therefore, the rise of the electricresistance of the source/drain region and the increase in junction leakcan be suppressed, and the performance of the first MOS transistor canbe improved.

According to the first semiconductor device of this invention, sincesilicide of a gate electrode excels a silicide layer of a source/drainregion in thermostability, when performing the silicidation of thesource/drain region after the silicidation of the gate electrode, it canbe prevented that the electrical property of the gate electrode changeswith the heat treatments by the silicidation of the source/drain region.Therefore, the performance of the MOS transistor can be improved.

According to the second semiconductor device of this invention, sincesilicidation of a source/drain region can be performed at lowtemperature, when performing the silicidation of the source/drain regionafter the silicidation of a gate electrode, it can be prevented that theelectrical property of the gate electrode changes by the heat treatmentby the silicidation of the source/drain region. Therefore, theperformance of the MOS transistor can be improved.

According to the third semiconductor device of this invention, a gateelectrode of the second MOS transistor in which p type impurities wereintroduced is formed more thinly than a gate electrode of the first MOStransistor in which n type impurities were introduced. Generally, in agate electrode into which p type impurities, such as a boron, wereintroduced, the speed of advance of the silicide reaction becomes slow.Therefore, the silicidation to the gate electrode in which the p typeimpurities were introduced, and the silicidation to the gate electrodein which the n type impurities were introduced can be ended almostsimultaneously like the present invention by forming thinly the gateelectrode with which the silicide reaction advances late. Therefore, thegate electrode in which the n type impurities were introduced is notexposed to the heat treatment more than needed, and the rise of theelectric resistance of the gate electrode concerned can be suppressed.As a result, the performance of the second MOS transistor can beimproved.

According to the fourth semiconductor device of this invention, since anupper surface of a silicide layer of a source/drain region is located inthe 5 nm or more upper part rather than the upper surface of the portionon which a gate insulating film is formed in a semiconductor substrate,the area of the boundary region of the source/drain region concerned andthe channel region of the first MOS transistor can be reducedmaintaining the thickness of the whole source/drain region including thesilicide layer. Therefore, it becomes difficult for the impurities inthe source/drain region to diffuse to the channel region of the firstMOS transistor by the heat treatment at the time of siliciding the gateelectrode. Therefore, degradation of the short channel characteristicsof the first MOS transistor can be prevented, and the performance can beimproved.

Since the upper surface of the silicide layer of the source/drain regionis located in the 5 nm or more upper part rather than the upper surfaceof the portion on which the gate insulating film is formed in thesemiconductor substrate, thickness of the silicide layer can bethickened. Since it will be hard to be influenced by heat treatment whenthe silicide layer is thick, it becomes difficult to generate cohesionof silicide. Therefore, when siliciding the gate electrode aftersiliciding the source/drain region, the cohesion generated in thesilicide layer of the source/drain region by the heat treatment by thesilicidation of the gate electrode can be suppressed. Therefore, therise of the electric resistance in the source/drain region and theincrease in junction leak can be suppressed, and the performance of thefirst MOS transistor can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing the structure of thesemiconductor device concerning Embodiment 1 of the present invention;

FIGS. 2 to 16 are cross-sectional views showing the manufacturing methodof the semiconductor device concerning Embodiment 1 of the presentinvention at process order;

FIGS. 17 to 20 are cross-sectional views showing the first modificationof the manufacturing method of the semiconductor device concerningEmbodiment 1 of the present invention at process order;

FIGS. 21 to 23 are cross-sectional views showing the second modificationof the manufacturing method of the semiconductor device concerningEmbodiment 1 of the present invention at process order;

FIGS. 24 to 27 are cross-sectional views showing the third modificationof the manufacturing method of the semiconductor device concerningEmbodiment 1 of the present invention at process order;

FIG. 28 is a cross-sectional view showing the structure of thesemiconductor device concerning Embodiment 2 of the present invention;

FIGS. 29 to 39 are cross-sectional views showing the manufacturingmethod of the semiconductor device concerning Embodiment 2 of thepresent invention at process order;

FIG. 40 is a cross-sectional view showing the first modification of thestructure of the semiconductor device concerning Embodiment 2 of thepresent invention;

FIG. 41 is a cross-sectional view showing the second modification of thestructure of the semiconductor device concerning Embodiment 2 of thepresent invention;

FIGS. 42 to 44 are cross-sectional views showing the first modificationof the manufacturing method of the semiconductor device concerningEmbodiment 2 of the present invention at process order; and

FIGS. 45 to 49 are cross-sectional views showing the second modificationof the manufacturing method of the semiconductor device concerningEmbodiment 2 of the present invention at process order.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1

FIG. 1 is a cross-sectional view showing the structure of thesemiconductor device concerning Embodiment 1 of the present invention.As shown in FIG. 1, the semiconductor device concerning Embodiment 1 isprovided with the nMOS region in which nMOS transistor 5 is formed, andthe pMOS region in which pMOS transistor 15 is formed. In thesemiconductor device concerning Embodiment 1, semiconductor substrate 1which is a p type silicon substrate, for example is formed. In the uppersurface of semiconductor substrate 1 in the boundary of the nMOS regionand the pMOS region, element isolation insulating film 2 which includesa silicon oxide film, for example is formed, and nMOS transistor 5 andpMOS transistor 15 are electrically separated by the element isolationinsulating film 2 concerned. Element isolation insulating film 2concerning Embodiment 1 is formed by the trench isolation method.

P type well region 3 is formed in the upper surface of semiconductorsubstrate 1 in an nMOS region, and n type well region 4 is formed in theupper surface of semiconductor substrate 1 in a pMOS region. In theupper surface of p type well region 3, two source/drain regions 6 ofnMOS transistor 5 are formed, separating mutually, and in the uppersurface of n type well region 4, two source/drain regions 16 of pMOStransistor 15 are formed, separating mutually. And silicide layer 7 isformed in the upper surface of source/drain region 6, and silicide layer17 is formed in the upper surface of source/drain region 16.

Source/drain region 6 of nMOS transistor 5 is an n type impurity region,and source/drain region 16 of pMOS transistor 15 is a p type impurityregion. Each of silicide layers 7 and 17 includes nickel silicide,cobalt silicide, platinum silicide, titanium silicides, or molybdenumsilicide, for example.

On the upper surface of p type well region 3 between source/drainregions 6, gate insulating film 8 and gate electrode 9 of nMOStransistor 5 are laminated in this order, and sidewall 10 is formed onthe both side surfaces of gate insulating film 8 and gate electrode 9.On the upper surface of n type well region 4 between source/drainregions 16, gate insulating film 18 and gate electrode 19 of pMOStransistor 15 are laminated in this order, and sidewall 20 is formed onthe both side surfaces of gate insulating film 18 and gate electrode 19.

Each of gate electrodes 9 and 19 is a FUSI gate electrode, and those allregions include silicide, such as nickel silicide, cobalt silicide,platinum silicide, titanium silicides, and molybdenum silicide. Each ofgate insulating films 8 and 18 includes high-k materials, such asaluminium oxide, for example, and each of sidewalls 10 and 20 includes asilicon nitride film. At Embodiment 1, the CMOS transistor includes nMOStransistor 5 and pMOS transistor 15.

Next, the manufacturing method of the semiconductor device shown in FIG.1 is explained. FIGS. 2-16 are the cross-sectional views showing themanufacturing method of the semiconductor device concerning Embodiment 1at process order. First, as shown in FIG. 2, while forming elementisolation insulating film 2 in the upper surface of semiconductorsubstrate 1, p type well region 3 and n type well region 4 are formed.

Next, as shown in FIG. 3, insulating film 80 which turns into gateinsulating films 8 and 18 at a later step is formed at the wholesurface. And as shown in FIG. 4, polysilicon film 90 which serves asgate electrodes 9 and 19 at a later step is formed on insulating film 80at the whole surface.

Next, as shown in FIG. 5, photoresist 200 is formed on polysilicon film80 in a pMOS region, the photoresist 200 concerned is used for a mask,and n type impurities 110 n, such as arsenic and phosphorus, areintroduced by ion-implantation into polysilicon film 90 in an nMOSregion. Then, photoresist 200 is removed.

Next, as shown in FIG. 6, photoresist 210 is formed on polysilicon film80 in an nMOS region, the photoresist 210 concerned is used for a mask,and p type impurities 110 p, such as boron and aluminium, are introducedby ion-implantation into polysilicon film 90 in a pMOS region. Then,photoresist 210 is removed.

Next, as shown in FIG. 7, polysilicon film 90 and insulating film 80 arepatterned one by one, and gate electrodes 9 and 19 which includepolysilicon film 90, respectively, and gate insulating films 8 and 18which include insulating film 80, respectively are formed. And theextension regions of nMOS transistor 5 and pMOS transistor 15 are formedin p type well region 3 and n type well region 4, respectively, andpocket implantation is performed after that.

Next, as shown in FIG. 8, insulating film 100 used as a sidewall isformed at the whole surface, covering gate insulating films 8 and 18 andgate electrodes 9 and 19. And silicon oxide film 120 is formed oninsulating film 100 at the whole surface. Insulating film 100 includes asilicon nitride film, for example.

Next, as shown in FIG. 9, silicon oxide film 120 is polished by the CMPmethod from the upper surface, using insulating film 100 as a stopperfilm. Hereby, silicon oxide film 120 is removed partially and the uppersurface of the portion located on gate electrode 9 and the upper surfaceof the portion located on gate electrode 19 are exposed in insulatingfilm 100.

Next, as shown in FIG. 10, exposed insulating film 100 is selectivelyremoved using a dry etching method which has selectivity to siliconoxide film 120, and each upper surface of gate electrodes 9 and 19 isexposed. At this time, silicon oxide film 120 functions as a protectivefilm to insulating film 100 which has not been exposed.

Next, as shown in FIG. 11, silicon oxide film 120 is selectively removedusing a wet etching method. And as shown in FIG. 12, in order tosilicide gate electrodes 9 and 19, metallic materials 130, such asnickel (Ni), cobalt (Co), platinum (Pt), titanium (Ti), and molybdenum(Mo), are deposited at the whole surface, and a heat treatment isperformed to the acquired structure. Metallic material 130 and thesilicon in contact with it react by this, and all the regions of gateelectrodes 9 and 19 which include polysilicon are silicided. Then,unreacted metallic material 130 is removed. Hereby, as shown in FIG. 13,gate electrodes 9 and 19 of FUSI gate electrodes are completed.

Next, as shown in FIG. 14, insulating film 100 is selectively etchedusing an anisotropic dry etching method with which the etching rate ishigh to the thickness direction of semiconductor substrate 1. By this,insulating film 100 is removed partially, sidewall 10 which includesinsulating film 100 is completed on the side face of gate insulatingfilm 8 and gate electrode 9, and sidewall 20 which includes insulatingfilm 100 is completed on the side face of gate insulating film 18 andgate electrode 19.

Next, as shown in FIG. 15, in p type well region 3, an n type,high-concentration impurity is introduced by ion-implantation,source/drain region 6 is formed, in n type well region 4, a p typehigh-concentration impurity is introduced by ion-implantation, andsource/drain region 16 is formed. Then, as shown in FIG. 16, in order tosilicide source/drain regions 6 and 16, metallic materials 140, such asnickel, cobalt, platinum, titanium, and molybdenum, are deposited at thewhole surface, and a heat treatment is performed to the acquiredstructure. Metallic material 140 and the silicon in contact with itreact by this, each of source/drain regions 6 and 16 is silicided, andsilicide layers 7 and 17 are formed. Then, unreacted metallic material140 is removed. As a result, the semiconductor device shown in FIG. 1 iscompleted. In Embodiment 1, the same material as metallic material 130is used for metallic material 140.

As mentioned above, in the manufacturing method of the semiconductordevice concerning Embodiment 1, the silicidation of source/drain regions6 and 16 is performed after the silicidation to gate electrodes 9 and19. Therefore, in the case of the silicidation of gate electrodes 9 and19, silicide does not exist in source/drain regions 6 and 16. Therefore,silicide does not cohere in source/drain regions 6 and 16 by the heattreatment in the case of the silicidation of gate electrodes 9 and 19.Therefore, junction leak can be reduced, while being able to eliminatethe adverse effect by silicide cohering and being able to reduce theelectric resistance of source/drain regions 6 and 16. As a result, theperformance of nMOS transistor 5 or pMOS transistor 15 can be improved.

Since the thickness of gate electrodes 9 and 19 is very larger than thediffusion depth of source/drain regions 6 and 16, the heat treating timein the silicidation of source/drain regions 6 and 16 is usually veryshorter than the heat treating time in the silicidation of gateelectrodes 9 and 19. Generally, the more the volume of silicide islarge, the more it is hard to generate the cohesion by heat. From thesereasons, in gate electrode 9 and 19, cohesion of silicide hardly arisesby the heat treatment by the silicidation of source/drain regions 6 and16. Therefore, the heat treatment by the silicidation of source/drainregions 6 and 16 hardly affects the electrical property of gateelectrodes 9 and 19, and does not pose a problem.

Although source/drain regions 6 and 16 are silicided after silicidingall the regions of gate electrodes 9 and 19 in the manufacturing methodconcerning above-mentioned Embodiment 1, source/drain regions 6 and 16,and the remaining portion of gate electrodes 9 and 19 may be silicidedsimultaneously after siliciding gate electrodes 9 and 19 partially.Below, the manufacturing method in this case is explained.

FIGS. 17-20 are the cross-sectional views showing the modification ofthe manufacturing method of the semiconductor device concerningEmbodiment 1 at process order. First, the manufacture is made to thestructure shown in FIG. 12 using the above-mentioned manufacturingmethod. And a heat treatment is performed to the acquired structure, andas shown in FIG. 17, gate electrodes 9 and 19 are silicided partially.This partial silicidation is realizable by adjusting the thickness andheat treating time of metallic material 130. Then, unreacted metallicmaterial 130 is removed.

Next, as shown in FIG. 18, sidewalls 10 and 20 are formed, etchinginsulating film 100 like an above-mentioned method, and as shown in FIG.19 after that, source/drain regions 6 and 16 are formed like anabove-mentioned method.

Next, as shown in FIG. 20, metallic material 140 is formed at the wholesurface, and a heat treatment is performed to the acquired structure.Hereby, source/drain regions 6 and 16 are silicided, and simultaneouslyall the regions of the portion which is not yet silicided of gateelectrodes 9 and 19 are silicided. Then, removal of unreacted metallicmaterial 140 will acquire the same structure as the semiconductor deviceshown in FIG. 1.

Thus, in siliciding simultaneously source/drain regions 6 and 16, andthe remaining portion of gate electrodes 9 and 19 after siliciding gateelectrodes 9 and 19 partially, in the case of the silicidation of thebeginning of gate electrodes 9 and 19, since silicide does not exist insource/drain regions 6 and 16, silicide does not cohere in source/drainregions 6 and 16 by the heat treatment in the case of the silicidationof the beginning of gate electrodes 9 and 19. Since the silicidation ofthe remaining portion of gate electrodes 9 and 19 and the silicidationof source/drain regions 6 and 16 are performed simultaneously, in thesilicidation of the remaining portion of gate electrodes 9 and 19,silicide does not cohere in source/drain regions 6 and 16. Therefore,the adverse effect by silicide cohering can be eliminated and theperformance of nMOS transistor 5 or pMOS transistor 15 can be improved.

Different materials may be used although the same material is used inEmbodiment 1 as to metallic material 130 used when siliciding gateelectrodes 9 and 19 and metallic material 140 used when silicidingsource/drain regions 6 and 16. Hereby, selection of a suitable metallicmaterial is attained in each of gate electrodes 9 and 19 andsource/drain regions 6 and 16.

For example, when cobalt is used as metallic material 130 and nickel andpalladium are used as metallic material 140, gate electrodes 9 and 19are formed by cobalt silicide, and silicide layers 7 and 17 ofsource/drain regions 6 and 16 come to be formed by nickel silicide orpalladium silicide. Generally, since cobalt silicide excels nickelsilicide and palladium silicide in thermostability, an electricalproperty seldom changes with heat treatments. Therefore, it can besuppressed that the electrical property of gate electrodes 9 and 19changes in the case of the heat treatment by the silicidation ofsource/drain regions 6 and 16. As a result, the performance of nMOStransistor 5 and pMOS transistor 15 can be improved further.

Since nickel and palladium generate a silicide reaction at lowtemperature rather than cobalt, when cobalt is used as metallic material130 and nickel and palladium are used as metallic material 140, thesilicidation of source/drain regions 6 and 16 can be performed at lowtemperature rather than the silicidation of gate electrodes 9 and 19.Therefore, it can be suppressed that the silicide in gate electrode 9and 19 coheres with the heat treatments by the silicidation ofsource/drain regions 6 and 16, and it can be prevented that theelectrical property of the gate electrodes 9 and 19 concerned changes.As a result, the performance of nMOS transistor 5 and pMOS transistor 15can be improved further.

It is more desirable to use palladium rather than nickel as metallicmaterial 140, since the case of using palladium as metallic material 140generates a silicide reaction at further low temperature rather than thecase where nickel is used.

Although silicon oxide film 120 was used as a protective film to theportion where insulating film 100 has not exposed and the portion whereinsulating film 100 has exposed is selectively removed in Embodiment 1in the step shown in FIG. 10, photoresist 220 may be used as aprotective film instead of silicon oxide film 120. Below, themanufacturing method in this case is explained.

FIGS. 21-23 are the drawings showing another modification of themanufacturing method of the semiconductor device concerning Embodiment 1at process order. First, the manufacture is made to the structure shownin FIG. 7 using the above-mentioned manufacturing method. And as shownin FIG. 21, insulating film 100 used as a sidewall is formed at thewhole surface, covering gate insulating films 8 and 18 and gateelectrodes 9 and 19, and photoresist 220 is formed on insulating film100 after that at the whole surface.

Next, as shown in FIG. 22, photoresist 220 is selectively and partiallyremoved using a dry etching method, and the upper surface of the portionlocated on gate electrode 9 and the upper surface of the portion locatedon gate electrode 19 are exposed in insulating film 100.

Next, as shown in FIG. 23, using a dry etching method which hasselectivity to photoresist 220, the exposing portion of insulating film100 is removed selectively, and each upper surface of gate electrodes 9and 19 is exposed. Then, the remaining photoresist 220 is removedselectively.

Thus, the alternative of a material employable as insulating film 100used as sidewalls 10 and 20 is expanded by using photoresist 220 as aprotective film to the portion where insulating film 100 has notexposed. Like the above-mentioned manufacturing method, when siliconoxide film 120 is used as a protective film, in order to secureselectivity, a silicon oxide film cannot be used as a material ofinsulating film 100. On the other hand, when photoresist 220 is used asa protective film, a silicon oxide film can be used as a material ofinsulating film 100. Therefore, insulating film 100 used as sidewalls 10and 20 can be formed by a single layer film, such as a silicon oxidefilm and a silicon nitride film, the two layer film of a silicon nitridefilm and a silicon oxide film, or three layer film of a silicon oxidefilm, a silicon nitride film, and a silicon oxide film, and the width ofthe material selection of sidewalls 10 and 20 spreads.

In Embodiment 1, although gate electrode 9 of nMOS transistor 5including n type impurities 110 n is formed by the same thickness asgate electrode 19 of pMOS transistor 15 including p type impurities 110p, gate electrode 19 may be formed more thinly than gate electrode 9.The manufacturing method in this case is explained below.

FIGS. 24-27 are the cross-sectional views showing another modificationof the manufacturing method of the semiconductor device concerningEmbodiment 1 at process order. First, the manufacture is made to thestructure shown in FIG. 11 using the above-mentioned manufacturingmethod. And as shown in FIG. 24, photoresist 230 which covers an nMOSregion is formed.

Next, photoresist 230 is used for a mask, dry etching is performed toexposed gate electrode 19, and the gate electrode 19 concerned isremoved partially. Then, photoresist 230 is removed. Hereby, as shown inFIG. 25, the thickness of gate electrode 19 including p type impurities110 p becomes thinner than gate electrode 9 including 110 n of n typeimpurities.

Next, as shown in FIG. 26, metallic material 130 is formed at the wholesurface. And a heat treatment is performed to the acquired structure andall the regions of gate electrodes 9 and 19 are silicided. Then, whensource/drain regions 6 and 16 are silicided and sidewalls 10 and 20 areformed similarly, the semiconductor device shown in FIG. 27 will beobtained.

Generally, in the gate electrode into which p type impurities, such as aboron, were introduced, the speed of advance of a silicide reactionbecomes slow as compared with the gate electrode into which n typeimpurities were introduced. Therefore, when gate electrode 9 including ntype impurities 110 n is formed by the same thickness as gate electrode19 including p type impurities 110 p, the side of the silicidation togate electrode 9 is completed earlier than the silicidation to gateelectrode 19, and the heat treatment more than needed is applied to gateelectrode 9. As a result, the electric resistance of gate electrode 9may rise.

In the above-mentioned modification, since gate electrode 19 with whicha silicide reaction becomes slow is formed thinly, the silicidation togate electrode 19 and the silicidation to gate electrode 9 can be endedalmost simultaneously. Therefore, n type gate electrode 9 is not exposedto a heat treatment more than needed. As a result, the rise of theelectric resistance of n type gate electrode 9 can be suppressed, andthe performance of nMOS transistor 5 can be improved.

Embodiment 2

FIG. 28 is a cross-sectional view showing the structure of thesemiconductor device concerning Embodiment 2 of the present invention.Although silicide layers 7 and 17 were formed in the upper surface ofsemiconductor substrate 1 in the semiconductor device concerningabove-mentioned Embodiment 1, silicide layers 7 and 17 are formed on theupper surface of semiconductor substrate 1 in the semiconductor deviceconcerning Embodiment 2. Therefore, the upper surface of silicide layer7 is located up rather than the upper surface of the portion on whichgate insulating film 8 is formed in semiconductor substrate 1, and theupper surface of silicide layer 17 is located up rather than the uppersurface of the portion on which gate insulating film 18 is formed insemiconductor substrate 1. Concretely, the upper surface of silicidelayers 7 and 17 is located in the 5 nm or more upper part, respectivelyrather than the upper surface of the portion on which gate insulatingfilms 8 and 18 are formed in semiconductor substrate 1. Since it is thesame as that of the semiconductor device concerning Embodiment 1 aboutother structures, the explanation is omitted.

Thus, in the semiconductor device concerning Embodiment 2, the uppersurface of silicide layer 7 of source/drain region 6 is located in the 5nm or more upper part rather than the upper surface of the portion onwhich gate insulating film 8 is formed in semiconductor substrate 1, inother words the portion in contact with gate insulating film 8 in theupper surface of semiconductor substrate 1. Therefore, maintainingthickness d1 of the source/drain region 6 whole including silicide layer7 to the same value as the thickness d1 concerned of the semiconductordevice concerning Embodiment 1 shown in FIG. 1, as shown in FIG. 28, thearea of boundary region 300 of source/drain region 6 and channel regionCNn of nMOS transistor 5 can be reduced. Therefore, it becomes difficultfor the impurity in source/drain region 6 to diffuse to channel regionCNn by the heat treatment at the time of siliciding gate electrode 9.Therefore, degradation of the short channel characteristics of nMOStransistor 5 can be prevented, and the performance of nMOS transistor 5can be improved.

Since the upper surface of silicide layer 7 is located in the 5 nm ormore upper part rather than the upper surface of the portion on whichgate insulating film 8 is formed in semiconductor substrate 1, silicidelayer 7 can be formed thickly as compared with the semiconductor deviceconcerning Embodiment 1. Since it will generally be hard to beinfluenced by heat treatment when silicide layer 7 is thick, it becomesdifficult to generate cohesion of silicide. Therefore, when silicidinggate electrode 9 after siliciding source/drain region 6, the cohesiongenerated in silicide layer 7 by the heat treatment by the silicidationof gate electrode 9 can be suppressed. As a result, the rise of theelectric resistance in source/drain region 6 and the increase injunction leak can be suppressed, and the performance of nMOS transistor5 can be improved.

The same thing can be said also about pMOS transistor 15. When the uppersurface of silicide layer 17 is located in the 5 nm or more upper partrather than the upper surface of the portion on which gate insulatingfilm 18 is formed in semiconductor substrate 1, the performance of pMOStransistor 15 can be improved.

Next, the manufacturing method of the semiconductor device shown in FIG.28 is explained. FIGS. 29-39 are the cross-sectional views showing themanufacturing method of the semiconductor device concerning Embodiment 2at process order. First, the manufacture is made to the structure shownin FIG. 4 using the manufacturing method concerning Embodiment 1. Andlike Embodiment 1, n type impurities 110 n are introduced intopolysilicon film 90 in an nMOS region, and p type impurities 110 p areintroduced into polysilicon film 90 in a pMOS region.

Next, as shown in FIG. 29, silicon nitride film 150 is formed onpolysilicon film 90. And silicon nitride film 150, polysilicon film 90,and insulating film 80 are patterned one by one. Hereby, as shown inFIG. 30, gate electrodes 9 and 19 which include polysilicon film 90, andgate insulating films 8 and 18 which include insulating film 80 arecompleted, and silicon nitride film 150 is formed on each of gateelectrodes 9 and 19. Then, the extension regions of nMOS transistor 5and pMOS transistor 15 are formed in p type well region 3 and n typewell region 4, respectively, and pocket implantation is performed.

Next, as shown in FIG. 31, insulating film 100 used as a sidewall isformed at the whole surface, covering silicon nitride film 150, gateinsulating films 8 and 18, and gate electrodes 9 and 19. And as shown inFIG. 32, sidewalls 10 and 20 are formed, selectively removing insulatingfilm 100 using an anisotropic dry etching method with which an etchingrate is high to the thickness direction of semiconductor substrate 1.Sidewall 10 is formed not only on the side face of gate insulating film8 and gate electrode 9 but on the side face of silicon nitride film 150on gate electrode 9 at this time. Similarly, sidewall 20 is formed notonly on the side face of gate insulating film 18 and gate electrode 19but on the side face of silicon nitride film 150 on gate electrode 19.

Next, as shown in FIG. 33, semiconductor layer 30 which includes asilicon layer is formed at 5 nm or more in thickness with epitaxialgrowth all over the upper surface of exposed semiconductor substrate 1,for example. Hereby, semiconductor layer 30 is formed on p type wellregion 3 so that the sidewall 10 concerned may be contacted in the sideof gate insulating film 8, gate electrode 9, and sidewall 10 of nMOStransistor 5. Simultaneously, semiconductor layer 30 is formed on n typewell region 4 so that the sidewall 20 concerned may be contacted in theside of gate insulating film 18, gate electrode 19, and sidewall 20 ofpMOS transistor 15.

Next, an n type, high-concentration impurity is introduced byion-implantation in semiconductor layer 30 in an nMOS region, and p typewell region 3 under it, and a p type high-concentration impurity isintroduced by ion-implantation in semiconductor layer 30 in a pMOSregion, and n type well region 4 under it. By this, as shown in FIG. 34,source/drain region 6 of nMOS transistor 5 is formed in semiconductorlayer 30 and p type well region 3 in an nMOS region, and source/drainregion 16 of pMOS transistor 15 is formed in semiconductor layer 30 andn type well region 4 in a pMOS region. Then, in order to silicidesource/drain regions 6 and 16, metallic material 140 is deposited at thewhole surface.

Next, a heat treatment is performed to the acquired structure, all theregions of semiconductor layer 30 are silicided, and unreacted metallicmaterial 140 is removed after that. Hereby, as shown in FIG. 35,silicide layers 7 and 17 are formed in source/drain regions 6 and 16,respectively.

Since silicide layers 7 and 17 are formed by siliciding semiconductorlayer 30 with a thickness of 5 nm or more formed on semiconductorsubstrate 1 from the upper surface, the upper surface of silicide layers7 and 17 comes to be located in the 5 nm or more upper part,respectively rather than the upper surface of the portion on which gateinsulating films 8 and 18 are formed in semiconductor substrate 1.

Since the side faces of gate electrodes 9 and 19 are covered bysidewalls 10 and 20, respectively and those upper surfaces are coveredwith silicon nitride film 150, gate electrodes 9 and 19 are notsilicided in the case of the silicidation of source/drain regions 6 and16.

Next, as shown in FIG. 36, interlayer insulation film 40 is formed atthe whole surface. And interlayer insulation film 40 is polished fromthe upper surface using a CMP method which uses silicon nitride film 150on gate electrode 9 and 19 as a stopper layer. And exposed siliconnitride film 150 is removed by performing dry etching. Hereby, as shownin FIG. 37, the upper surfaces of gate electrodes 9 and 19 are exposed.

Next, as shown in FIG. 38, in order to silicide gate electrodes 9 and19, metallic material 130 is formed at the whole surface. And a heattreatment is performed to the acquired structure and all the regions ofgate electrodes 9 and 19 are silicided. Then, unreacted metallicmaterial 130 is removed. Hereby, as shown in FIG. 39, gate electrodes 9and 19 of a FUSI gate electrode are completed. Then, the structure shownin FIG. 28 is completed by forming interlayer insulation film 50 at thewhole surface.

After formation of interlayer insulation film 50, a contact step isusually performed and the contact plug which is not illustrated isformed in interlayer insulation film 40 and 50.

As mentioned above, in the manufacturing method of the semiconductordevice concerning Embodiment 2, semiconductor layer 30 is formed onsemiconductor substrate 1, and source/drain region 6 is formed in thesemiconductor layer 30. Therefore, it becomes difficult for the impurityin source/drain region 6 to diffuse to the channel region of nMOStransistor 5 by the heat treatment by the silicidation of gate electrode9. Therefore, degradation of the short channel characteristics of nMOStransistor 5 can be prevented, and the performance of nMOS transistor 5improves.

Since source/drain region 6 formed in semiconductor layer 30 issilicided, silicide layer 7 in source/drain region 6 can be thicklyformed by adjusting the thickness of semiconductor layer 30. Since itwill be hard to be influenced by heat treatment when silicide layer 7 isthick, it becomes difficult to generate cohesion of silicide. Therefore,the cohesion generated in silicide layer 7 of source/drain region 6 bythe heat treatment by the silicidation of gate electrode 9 can besuppressed. As a result, the rise of the electric resistance insource/drain region 6 and the increase in junction leak can besuppressed, and the performance of nMOS transistor 5 can be improved.The same thing can be said also about pMOS transistor 15, and theperformance of pMOS transistor 15 can be improved.

In Embodiment 2, semiconductor layer 30 is formed by epitaxial growth.Generally, in the semiconductor layer formed by epitaxial growth, sinceit is harder to diffuse an impurity than the semiconductor layer ofpolycrystals, such as a polysilicon layer, diffusion of the impurity insource/drain region 6 and 16 by the heat treatment by the silicidationof gate electrodes 9 and 19 can be suppressed. Therefore, degradation ofthe short channel characteristics of nMOS transistor 5 or pMOStransistor 15 can be prevented.

In Embodiment 2, although all the regions of semiconductor layer 30 weresilicided, silicide layers 7 and 17 may be formed, partially silicidingsemiconductor layer 30 from the upper surface. In the semiconductordevice formed by doing in this way, as shown in FIG. 40, silicide layers7 and 17 are formed on semiconductor substrate 1 via semiconductor layer30.

When siliciding source/drain regions 6 and 16, not only semiconductorlayer 30 but the inside of the upper surface of semiconductor substrate1 may be silicided. Hereby, the semiconductor device shown in FIG. 41 isobtained.

Just before forming interlayer insulation film 40, a silicon nitridefilm (not shown) may be formed at the whole surface, and interlayerinsulation film 40 may be formed on the silicon nitride film concerned.In this case, when forming a contact hole in interlayer insulation films40 and 50 at a later step, dry etching can be stopped with the siliconnitride film concerned. Hereby, the amount of over-etchings at the timeof forming a contact hole can be reduced.

Mutually different materials may be used for metallic material 130 usedwhen siliciding gate electrodes 9 and 19, and metallic material 140 usedwhen siliciding source/drain regions 6 and 16. Hereby, selection of asuitable metallic material is attained in each of gate electrodes 9 and19 and source/drain regions 6 and 16.

In Embodiment 2, since unlike Embodiment 1 gate electrodes 9 and 19 aresilicided after siliciding source/drain regions 6 and 16, nickel andpalladium are used as metallic material 130, and cobalt is used asmetallic material 140, for example. When it does so, unlike Embodiment1, gate electrodes 9 and 19 will be formed by nickel silicide orpalladium silicide, and silicide layers 7 and 17 of source/drain regions6 and 16 will come to be formed by cobalt silicide. As mentioned above,generally, since cobalt silicide excels nickel silicide and palladiumsilicide in thermostability, the electrical property seldom changes withheat treatments. Therefore, it can be suppressed that the electricalproperty of source/drain regions 6 and 16 changes in the case of theheat treatment by the silicidation of gate electrodes 9 and 19. As aresult, the performance of nMOS transistor 5 and pMOS transistor 15 canbe improved further.

Since nickel and palladium generate a silicide reaction at lowtemperature rather than cobalt, when nickel and palladium are used asmetallic material 130 and cobalt is used as metallic material 140, thesilicidation of gate electrodes 9 and 19 can be performed at lowtemperature rather than the silicidation of source/drain regions 6 and16. Therefore, it can be suppressed that the silicide in silicide layer7 and 17 of source/drain regions 6 and 16 coheres with the heattreatments by the silicidation of gate electrodes 9 and 19, and it canbe prevented that the electrical property of the source/drain regions 6and 16 concerned changes.

It is more desirable to use palladium rather than nickel as metallicmaterial 130, since the case of using palladium as metallic material 130generates a silicide reaction at further low temperature rather than thecase where nickel is used.

In Embodiment 2, although gate electrode 9 of nMOS transistor 5including n type impurities 110 n is formed by the same thickness asgate electrode 19 of pMOS transistor 15 including p type impurities 110p, gate electrode 19 may be formed more thinly than gate electrode 9.The manufacturing method in this case is explained below.

FIGS. 42-44 are the cross-sectional views showing the modification ofthe manufacturing method of the semiconductor device concerningEmbodiment 2 at process order. First, the manufacture is made to thestructure shown in FIG. 37 using the above-mentioned manufacturingmethod. And as shown in FIG. 42, photoresist 240 which covers an nMOSregion is formed, the photoresist 240 concerned is used for a mask, dryetching is performed to exposed gate electrode 19, and the gateelectrode 19 concerned is removed partially. Hereby, the thickness ofgate electrode 19 becomes thinner than gate electrode 9. Then,photoresist 240 is removed.

Next, as shown in FIG. 43, metallic material 130 is formed at the wholesurface. And a heat treatment is performed to the acquired structure andall the regions of gate electrodes 9 and 19 are silicided. Then, whenunreacted metallic material 130 is removed and interlayer insulationfilm 50 is formed, the semiconductor device shown in FIG. 44 will beobtained.

As mentioned above, generally with the gate electrode into which p typeimpurities, such as a boron, were introduced, the speed of advance of asilicide reaction becomes slow as compared with the gate electrode intowhich the n type impurities were introduced. Therefore, like theabove-mentioned modification, the silicidation to p type gate electrode19 and the silicidation to n type gate electrode 9 can be ended almostsimultaneously by forming thinly gate electrode 19 with which a silicidereaction becomes slow. Therefore, n type gate electrode 9 is not exposedto a heat treatment more than needed, and the rise of electricresistance of n type gate electrode 9 can be suppressed.

The upper surface of semiconductor substrate 1 may be dug downpartially, and semiconductor layer 30 may be formed at the dug-downportion. The manufacturing method in this case is explained below.

FIGS. 45-49 are the cross-sectional views showing another modificationof the manufacturing method of the semiconductor device concerningEmbodiment 2 at process order. First, the manufacture is made to thestructure shown in FIG. 32 using the above-mentioned manufacturingmethod. And the exposing portion of semiconductor substrate 1 is removedpartially, using a dry etching method etc. Hereby, as shown in FIG. 45,in the side of gate insulating film 8 and gate electrode 9, and the sideof gate insulating film 18 and gate electrode 19, the upper surface ofsemiconductor substrate 1 is dug down partially.

Next, as shown in FIG. 46, semiconductor layer 30 is formed all over theexposed upper surface of semiconductor substrate 1. Hereby,semiconductor layer 30 is formed at the dug-down portion ofsemiconductor substrate 1. At this time, the thickness of semiconductorlayer 30 is set as a value at which the upper surface of thesemiconductor layer 30 concerned is located in the 5 nm or more upperpart rather than the upper surface of the portion on which gateinsulating films 8 and 18 are formed in semiconductor substrate 1.

Next, as shown in FIG. 47, like the above-mentioned manufacturingmethod, source/drain region 6 is formed in semiconductor layer 30, and ptype well region 3 under it in an nMOS region, and source/drain region16 is formed in semiconductor layer 30, and n type well region 4 underit in a pMOS region. And in order to silicide source/drain regions 6 and16, metallic material 140 is deposited at the whole surface.

Next, a heat treatment is performed to the acquired structure, all theregions of semiconductor layer 30 are silicided, and unreacted metallicmaterial 140 is removed after that. Hereby, as shown in FIG. 48,silicide layers 7 and 17 are formed in source/drain regions 6 and 16,respectively. The upper surface of silicide layers 7 and 17 at this timecomes to be located in the 5 nm or more upper part like thesemiconductor device shown in FIG. 28 rather than the upper surface ofthe portion on which gate insulating films 8 and 18 are formed insemiconductor substrate 1. Since semiconductor layer 30 is formed at theportion at which semiconductor substrate 1 was dug down, the undersurface of silicide layers 7 and 17 comes to be located below ratherthan the upper surface of the portion on which gate insulating films 8and 18 are formed in semiconductor substrate 1.

Then, like the above-mentioned manufacturing method, the structure shownin FIG. 49 is acquired by forming interlayer insulation film 40,siliciding gate electrodes 9 and 19, and forming interlayer insulationfilm 50.

Thus, the damages with which the upper surface of semiconductorsubstrate 1 received by then, such as the etching damage at the time offorming sidewalls 10 and 20, are removable by digging down the uppersurface of semiconductor substrate 1. As a result, the crystal defect insemiconductor layer 30 can be reduced, and junction leak in source/drainregions 6 and 16 formed in the semiconductor layer 30 concerned can bereduced.

When digging down the upper surface of semiconductor substrate 1partially and forming semiconductor layer 30 at the dug-down portionlike this modification, semiconductor layer 30 having included germaniummay be formed. Hereby, in source/drain region 6, germanium comes toexist over the lower part rather than the upper surface of the portionon which gate insulating film 8 is formed in semiconductor substrate 1from the upper surface, and in source/drain region 16, germanium comesto exist over the lower part rather than the upper surface of theportion on which gate insulating film 18 is formed in semiconductorsubstrate 1 from the upper surface.

Thus, by including germanium in semiconductor layer 30, a tensile strain(lattice strain) occurs in the boundary of the semiconductor layer 30concerned and the channel region of nMOS transistor 5 in semiconductorsubstrate 1, as a result, the electron mobility in nMOS transistor 5improves, and nMOS transistor 5 excellent in driving ability can berealized. Similarly, since a tensile strain (lattice strain) occurs inthe boundary of semiconductor layer 30 including germanium and thechannel region of pMOS transistor 15 in semiconductor substrate 1, theelectron mobility in pMOS transistor 15 improves, and pMOS transistor 15excellent in driving ability can be realized.

Since growing temperature can be set as low temperature when formingsemiconductor layer 30 including germanium by epitaxial growth,diffusion of impurities introduced into semiconductor substrate 1 bythen, such as impurities in the extension regions in nMOS transistor 5or pMOS transistor 15, can be suppressed. As a result, the semiconductordevice which has desired performance becomes easy to be obtained.

1. A semiconductor device, comprising: a semiconductor substrate; and aMOS transistor formed over the semiconductor substrate; wherein the MOStransistor includes: a source/drain region in which a silicide layer isformed; and a gate electrode with which all regions are formed withsilicide which excels the silicide layer of the source/drain region inthermostability.
 2. A semiconductor device, comprising: a semiconductorsubstrate; and a MOS transistor formed over the semiconductor substrate;wherein the MOS transistor includes: a source/drain region in which asilicide layer is formed; and a gate electrode with which all regionsare formed with silicide; wherein what generates a silicide reaction atlow temperature rather than a metallic material of the silicide of thegate electrode is used for a metallic material of the silicide layer ofthe source/drain region.
 3. A semiconductor device according to claim 1,wherein the gate electrode includes cobalt silicide; and the silicidelayer of the source/drain region includes nickel silicide or palladiumsilicide.